1. Field
The described technology relates generally to a rechargeable battery pack.
2. Description of the Related Art
A rechargeable battery differs from a primary battery in that a rechargeable battery can be repeatedly charged and discharged, while the latter only irreversibly converts chemical energy to electrical energy. A low-capacity rechargeable battery is typically used as the power supply for small electronic devices, such as cellular phones, notebook computers and camcorders, while the high-capacity rechargeable battery is typically used as the power supply for driving motors in hybrid vehicles and the like.
Types of rechargeable batteries include a nickel-cadmium battery, a lead-acid battery, a nickel-hydride battery, a lithium ion battery, and a lithium polymer battery. In particular, an operation voltage of the lithium ion secondary battery is three times higher than that of the nickel-cadmium battery used as a portable electronic equipment of the nickel hydride battery. In addition, the lithium ion secondary battery has been widely used because of high energy density per unit weight.
Some rechargeable batteries use a lithium-based oxide as a positive electrode active material and a carbon-based material as a negative electrode active material. In general, a rechargeable battery is classified as a liquid electrolyte battery or a polymer electrolyte battery according to the type of electrolyte, and a battery using the liquid electrolyte is called a lithium ion battery and a battery using the polymer electrolyte is called a lithium polymer battery.
When an impact is applied in a longitudinal direction to rechargeable batteries, the rechargeable batteries may become deformed, thereby being maintained in a dangerous state. When the rechargeable batteries are deformed, an internal short-circuit may occur. When the internal short-circuit occurs in a portion having high resistance, excessive heat may be generated in the rechargeable battery.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.